WeeklyDelight
Cooking guide

Pan and Tin Size: Why It Changes the Result

A recipe's tin size is part of the recipe. Change it and the same batter sits at a different depth, which changes how long it takes and how it rises.

The comparison that matters is area, at the same depth. A square or rectangular tin's area is its length times its width. A round tin's is half the diameter, squared, times pi (3.14). King Arthur Baking works through exactly this sum to show that an 8-inch square tin and a 9-inch round tin hold the same amount, about 64 square inches each, and can stand in for each other.

Some metric comparisons

  • A 20 cm square tin: 20 × 20 = 400 cm².
  • A 23 cm round tin: 11.5 × 11.5 × 3.14 ≈ 415 cm², close enough to swap for a 20 cm square.
  • A 20 cm round tin: 10 × 10 × 3.14 ≈ 314 cm², about a fifth smaller than the 20 cm square, so the same batter sits deeper.
  • A 23 × 33 cm traybake tin: 759 cm², almost twice the 20 cm square.

If the areas are close, use the recipe as written. If your tin is larger, the batter is shallower and will cook faster; if it is smaller, the batter is deeper, takes longer, and may need the heat lowered so the outside does not overbake before the middle sets. King Arthur also notes that depth matters for cakes and suggests keeping to tins of the depth the recipe assumes.

Check early, trust the cue

Whatever you change, start checking well before the recipe's time and rely on the doneness test the method gives: a skewer coming out clean, a hollow sound underneath, an even golden top. Those cues hold in any tin; the minutes do not.

Frying pans and trays

The same logic applies outside baking. A crowded frying pan or roasting tray tends to steam the food rather than brown it. If you scale a recipe up, use a bigger pan or two, or cook in batches, rather than piling more into the pan the recipe names.

Recipes that use this